Back to EveryPatent.com
United States Patent |
5,306,124
|
Back
|
April 26, 1994
|
Slurry pump and seal system
Abstract
A mud pump assembly has a housing having a motor-mounting face directly
connected to a standard hydraulic drive motor. The pump housing supports
and partially encloses a bearing assembly which supports the pump impeller
shaft. A face-type impeller shaft seal is located between the bearing
assembly and the impeller. The motor case completes enclosure of the
impeller shaft bearing assembly. A motor case drain line is coupled to the
mud pump housing for continuous pressure lubrication of the bearing
assembly. In one embodiment, case drain fluid is returned from the mud
pump housing to the hydraulic fluid reservoir for the hydraulic motor.
Inventors:
|
Back; Carl F. (Winter Haven, FL)
|
Assignee:
|
Laibe Supply Corporation (Indianapolis, IN)
|
Appl. No.:
|
036662 |
Filed:
|
March 24, 1993 |
Current U.S. Class: |
417/406 |
Intern'l Class: |
F04B 017/00 |
Field of Search: |
417/407,409,406,371
|
References Cited
U.S. Patent Documents
2149600 | Mar., 1939 | Guinard | 417/406.
|
2766695 | Oct., 1956 | Gailloud.
| |
3761205 | Sep., 1973 | Cronstedt.
| |
3890065 | Jun., 1975 | Ellen et al. | 417/407.
|
4272224 | Jun., 1981 | Kabele.
| |
Primary Examiner: Gluck; Richard E.
Attorney, Agent or Firm: Woodard, Emhardt, Naughton, Moriarty & McNett
Claims
What is claimed is:
1. Pumping apparatus comprising:
a hydraulic motor having a case and power output member, the output member
being driven by hydraulic fluid in a system wherein the hydraulic fluid is
supplied under pressure to the motor;
a pump impeller coupled to the motor output member and drivable by the
motor;
a bearing assembly supporting the impeller;
a bearing lubricator delivering a portion of the hydraulic fluid under
pressure to the bearing assembly;
a pump housing assembly having a cavity therein receiving the bearing
assembly and having a cavity therein receiving the impeller;
a seal separating the impeller cavity from the bearing cavity;
the pumping housing assembly being attached to the motor case; and
the motor case being bolted directly to the pump housing assembly at the
bearing cavity thereby closing the bearing cavity to contain hydraulic
fluid under pressure in the bearing cavity.
2. The apparatus of claim 1 and wherein:
the hydraulic motor has a hydraulic supply inlet, a hydraulic return outlet
and a case drain outlet;
the bearing lubricator includes a motor case drain passageway from the
motor case drain outlet to the bearing assembly receiving cavity and
entering the bearing assembly receiving cavity through a wall thereof at a
point radially outward from the bearing assembly.
3. The apparatus of claim 2 and further comprising:
a return line from the bearing assembly cavity to the system to return case
drain hydraulic fluid to the system.
4. The apparatus of claim 2 and further comprising:
means in the passageway to prevent movement of fluid in the passageway in a
direction away from the bearing assembly cavity, and to restrict flow
through the passageway into the cavity.
5. The apparatus of claim 4 and further comprising:
a motor case drain line returning fluid at motor case drain pressure form
the motor case drain outlet into the system.
6. Pumping apparatus comprising:
a hydraulic motor having a case with a motor drive fluid supply inlet and
return outlet and a case drain outlet and having a power output member;
a mud pump impeller coupled to the output member;
a bearing assembly between the motor and impeller and supporting the
impeller; and
a seal between the impeller and the bearing assembly to prevent fluids at
the impeller from communicating with the bearing assembly;
the case drain outlet communicating with the bearing assembly and applying
motor driving hydraulic fluid moved by case drain pressure and applying
the fluid from the case drain outlet at case drain pressure in the bearing
cavity and establishing a pressure drop across the seal from the bearing
assembly side of the seal to the impeller side of the seal.
7. The apparatus of claim 6 and wherein the motor case has a mounting
flange, the apparatus further comprising:
a pump housing around the impeller and bearing assembly and having a
mounting flange bolted directly to the mounting flange of the motor case
and having a bearing lubrication fluid inlet; and
a case drain line coupled to the motor case drain outlet and to the
lubrication fluid inlet and delivering the hydraulic fluid from the motor
case to the bearing assembly.
8. The apparatus of claim 7 and wherein:
the lubrication fluid inlet is located radially outward from the bearing
assembly.
9. The apparatus of claim 6 and further comprising:
a housing around the seal;
a shaft coupling the impeller to the motor output member;
the seal including a first ring fixed and sealed in the housing, and a
second ring rotatable with the shaft and axially slidable on the shaft and
sealed to the shaft,
the first and second rings having abutting sealing surfaces providing a
rotary seal.
10. The apparatus of claim 9 and further comprising:
a spring urging the first and second rings together at their abutting
sealing surfaces.
11. The apparatus of claim 6 and further comprising:
a mud pump housing assembly including a pump shaft support portion, an
impeller surrounding portion and an end cover, the housing assembly
thereby enclosing the impeller and having a mud inlet in the cover and a
mud outlet in the impeller surrounding portion,
the pump shaft support portion being fastened to the motor case and
cooperating with a portion of the motor case for enclosing the bearing
assembly.
12. The apparatus of claim 11 and wherein:
the pump shaft support portion has motor mounting face and a bore
communicating with the face and with the bearing assembly; and
the motor case has a pump mounting face and a cylindrical boss at the face
and fittingly received in the bore,
the motor case being sealed to the bearing support portion to contain the
hydraulic fluid in the bearing assembly.
13. The apparatus of claim 12 and wherein:
the mud inlet is in the center of the cover; and
the mud outlet is in the perimeter of the impeller surrounding portion;
the apparatus further comprising a shaft having the impeller fastened to
one end and having its other end coupled to the motor output member inside
the bearing assembly.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to mud pumps for use in water well
drilling operations, and more particularly to a motor driven
centrifugal-type mud pump assembly having a close-coupled direct drive
hydraulic motor and a case-drain-pressurized pump shaft seal assembly at
the mud pump impeller end of the shaft.
2. Description of the Prior Art
During water well drilling operations, it is usually necessary to pump
muddy water. Though some pumps are of a reciprocating type, most pumps
used for this purpose are rotary pumps, primarily because they are much
less expensive than reciprocating pumps. One problem that is very common
with rotary pumps is seal failure due to the abrasives in the mud being
pumped.
Many mud pumps are driven by a hydraulic motor through a coupling shaft
assembly such that the motor is spaced sufficiently from the pump for
access to a pump shaft seal packing housing to facilitate replacement of
seals. Depending upon the manner and environment of use of the pump, seal
failures can occur as often as daily, resulting in significant down-time
during replacement of a seal assembly. In addition, due to the necessity
of having enough space to change a seal, the pump and drive motor assembly
has an overall length that is objectionable.
Since the pump impeller has a high rotational speed, and must be supported
in the housing by suitable bearings, leakage of muddy water into the
bearing area is intolerable. At one time, asbestos was used as a component
of pump shaft seal packing. Health and environmental concerns have since
dictated the exclusion of asbestos from such materials, resulting in a
reduction in the packing life.
As is true of many mechanical devices, provisions are typically made for
greasing pump bearings by using a grease gun. But this requires regular
attention by an operator to be certain that greasing is done on a timely
and adequate basis. Also, it is important to avoid excessive pressure such
as could cause the blow-out of a shaft seal.
It is an object of the present invention to provide a mud pump shaft
sealing system facilitating close coupling of the pump and drive motor,
and providing comparatively long seal life.
SUMMARY OF THE INVENTION
Described briefly, according to a typical embodiment of the present
invention, a mud pump assembly is provided with a housing having a
motor-mounting face directly connected to a standard hydraulic drive
motor. The pump housing has a bearing receiving cavity therein which
contains a bearing assembly to support the pump impeller shaft and a
face-type shaft seal assembly between the bearing assembly and the
impeller. The motor case drain line is coupled to the bearing cavity in
the pump housing for continuous pressure lubrication of the impeller shaft
bearings and the seal assembly. PG,5
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a fragmentary elevational view of a mobile drilling rig showing a
pump and motor assembly in position for pumping mud from a shallow pit.
FIG. 2 is an enlarged fragmentary sectional view through the motor and pump
assembly showing internal details of the pump assembly.
FIG. 3 is a further enlarged fragmentary view showing the mounting of the
seal assembly.
FIG. 4 is a view similar to FIG. 1 but showing an alternate hydraulic
arrangement for bearing supply.
DESCRIPTION OF THE PREFERRED EMBODIMENT
For the purposes of promoting an understanding of the principles of the
invention, reference will now be made to the embodiment illustrated in the
drawings and specific language will be used to describe the same. It will
nevertheless be understood that no limitation of the scope of the
invention is thereby intended, such alterations and further modifications
in the illustrated device, and such further applications of the principles
of the invention as illustrated therein being contemplated as would
normally occur to one skilled in the art to which the invention relates.
Referring now to the drawings in detail, FIG. 1 shows fragmentarily a
portion of the rear of a truck having a bed 12 supported on frame side
members supported on dual wheels 13. A hydraulic pump assembly 14 mounted
to the truck includes a fixed displacement pump 15 and a charge pump 16,
both of which are driven by an input drive shaft 17 from a power take-off
or transfer case from the truck engine (not shown). The charge pump 16
takes hydraulic fluid from the supply reservoir 18 and delivers it to the
pump 15 for delivery under pressure and return through one or the other of
the lines 19 and 21 coupled from the hydraulic pump 15 to the hydraulic
motor 22. A motor case drain line 23 is returned, typically through the
hydraulic pump housing, to the reservoir 18 but shown directly returned in
FIG. 1. The determination of whether high or low pressure oil is in one or
the other lines 19 and 21 is typically controlled by a conventional pump
control system, this being a conventional type of hydrostatic transmission
or drive system employing a fixed displacement hydraulic motor 22 and
fixed displacement hydraulic pump 15 such as are well known in the art.
The mud pump assembly 24 is near the rear end of the truck. A hydraulic
truck-stabilizing jack assembly includes a housing 25 fixed to the truck
frame. A cylinder and piston rod assembly is located in the housing 25,
with the rod end up so that the foot 26 of the jack assembly is swivel
mounted to the bottom of the cylinder in conventional manner. An
upwardly-opening cylinder 27 is fastened to the foot and is vertically
slidable along the outside of the jack housing 25 as the jack is extended
and retracted. The mud pump is preferably mounted by means of upper and
lower brackets 28U and 28L, respectively, fastened to the cylinder 27 on
the foot of the left rear jack assembly so that, when the jack is extended
so that its foot 26 bears on the ground, the mud pump housing is near or
at ground level. These features are shown schematically in FIG. 1, as
their precise location on the truck frame may be varied, depending upon
the particular configuration of the truck, stabilizing jacks, and other
features. The jack mounting shafts may be driven by hydraulic power or
manually or otherwise, as desired. Also, the pump may be mounted on the
right rear jack foot or at another location on the truck, and the
orientation of the pump axis may be different from vertical, if desired.
According to one feature of the invention, the mud pump is close-coupled to
the hydraulic motor. In the illustrated embodiment, the mud pump housing
is bolted directly to the hydraulic motor case. Referring now specifically
to FIG. 2, the hydraulic motor 22 can be any of a variety of conventional
off-the-shelf hydraulic motors readily available from manufacturers and
having a conventional mounting flange 32 with pilot flange 33 and splined
output shaft 34 with a 12-24 pitch spline, 14 teeth, for example. An
example is the 21 Series Motor by Sundstrand of Ames, Iowa, U.S.A. Thus,
one feature of the pump assembly of this invention is the fact that its
mounting flange 36 bolts directly to the mounting flange 32 of the
hydraulic motor. An O-ring seal 37 is provided at the interface between
the pilot flange 33 of the motor and the pilot cavity wall 38 of the pump
housing assembly.
There are three major components of the pump housing assembly, namely the
bearing housing 41, center housing 42, and cover plate 43. Upper and lower
ball bearing assemblies 44 and 46 are received in a bearing cavity in the
bearing housing to support the impeller shaft 47, having an internal
spline received on the motor shaft spline 34. The impeller 48 is keyed at
49 near the lower, impeller-mounting end of the shaft, and secured by a
washer 51 and nut 52 at the lower end of the mud pump shaft. A replaceable
back plate 53 is fastened to the face 54 of the bearing housing by
circularly spaced socket head cap screws 56, with an O-ring interface seal
57 employed, if desired.
The center housing 42 is secured to the bearing housing by twelve
circularly-spaced bolts or stud-nut combinations. Three of the bolts, or
stud-nut combinations 58,59 are use to fasten the upper bracket 28U to the
bearing housing as well as the bearing housing to the center housing. The
mud pump discharge outlet 61 is at the perimeter of the center housing,
and internally threaded to receive discharge pipe 62 (FIG. 1). Paper
gaskets 63 are employed between the center housing and the cover plate 43
and bearing housing 41 to provide a seal at each of these locations. The
gaskets between the cover plate 43 and center housing 42 can be selected
to provide the desired axial clearance space 64 between lower edges of the
impeller blades and the upper face of the cover plate. At the upper face
of the impeller, the clearance 66 can be controlled by the thickness of
the plate 53 that is installed. The pump inlet is at the center of the
cover plate 43 and is internally threaded to receive an inlet pipe
fitting. In the illustrated example with the pump near ground level, a
street elbow is mounted in the inlet and connected to an intake hose whose
inlet is connected to a foot valve 67 submerged in the mud pit. Thus, the
pump remains primed. In any case, priming is easy.
Another feature of this invention is the use of the face seal assembly 68
in the bearing housing. This seal assembly includes a ring 69 which is
snugly and sealingly received in the step bore 71 in the bearing housing.
It does not rotate in the bearing housing. A spring biased seal ring 72 is
slidably but sealingly fitted to the shaft 47 and is biased by the coil
spring 73 to abuttingly engage and seal the lower face of seal ring 72
against the upper face of the seal ring 69. A spring seat collar 74 on
shaft 47 abuts the shaft shoulder 76 and serves as a pilot and seat for
the spring 73 at the upper end of the spring. It is intended that the
spring seat collar 74, spring 73 and seal ring 72 turn with the shaft.
Therefore, both of the seal rings 72 and 69 need to have good wearing and
sealing surfaces. An example of a low friction, wear resistant material
for ring 72 is sold under the trade name "Rulon A" by Dixon Industries,
Inc. of Clifton Heights, Pa. A glass filled "Teflon" can also be used for
this ring. The flat face 72F of this ring provides a running seal against
the flat face of the seal ring 69 which should have a hard, wear resistant
flat face 69F. Tungsten carbide may be a suitable material for the face
69F of the seal ring 69. A seal assembly which will work is made by the
E.G. & G. Sealol Incorporated of 455 West Fullerton, Elmhurst, Ill.
A grease fitting 77 is installed in the bearing housing as shown, at the
top of a passageway leading to the space between the impeller and the seal
assembly. This enables application of grease on a regular basis to the
pump housing assembly below the seal assembly at the impeller hub. Even
so, another feature of the present invention is the use of hydraulic fluid
at the motor case drain pressure to lubricate the pump bearings. For this
purpose, two threaded ports 78 and 79 are provided in the pump housing. A
hydraulic fluid line 81 is connected by a suitable threaded fitting into
port 78 of the pump housing and to the normal case drain port 82 of the
hydraulic motor 22. A case drain fluid return line 23 is connected to the
port 79 of the pump housing and returned to the reservoir 18. The motor
case drain fluid line 23 is shown connected through the pump housing where
it co-mingles with any case drain fluid in the pump housing and from which
it is returned directly or through a heat exchanger to the reservoir 18.
Of course, line 23 could be connected directly to the reservoir 18, if
desired.
As can be seen in the drawing FIG. 2, this arrangement enables the direct
application of the hydraulic fluid from the hydraulic motor at case drain
pressure to both of the ball bearing assemblies. The pressure is also
applied directly to the seal assembly.
The loading of spring 73 is established to require at least a 15 psi
pressure drop from the impeller side to the bearing side of the seal
assembly 68 for the seal to open.
In operation, with the mud pump drive motor at rest, the mud pump might or
might not be primed. In either case, there would be a spring load on the
bearing seal assembly, 10 pounds, for example. Therefore, the seal would
remain sealed regardless of temperature and regardless of whether or not
the pump is primed. During start-up and, if the pump is not primed (which
is the usual condition), rotation of the impeller may establish a vacuum
at the impeller side of the seal assembly. While such a vacuum might
normally pull the packing away from a conventional pump bearing seal, that
will not happen with the seal assembly of the present invention. The
vacuum would tend to close the seal. The spring 73 will assure that it is
closed. In addition, hydraulic fluid in the hydraulic pump 15 will soon
cause a rise in pressure in the case drain line which may rise to a point
anywhere from 10 to 45 psi, depending upon the nature and condition of the
hydraulic pump itself, and the resistance in the line 81 to the bearing
assembly, and from the bearing assembly through line 23 to the hydraulic
pump and from there to the reservoir 18. Therefore, there is normally a
pressure drop across the seal assembly from the bearing side to the
impeller side during all mud pump operating pressure conditions which
could range from zero to 10 to 15 psi output pressure.
Another factor contributing to maintenance of the closed condition of the
seal assembly is the fact that the area of the seal ring 72 exposed to the
impeller pressure is about half the area thereof exposed to the case drain
fluid pressure. Therefore, for a given amount of hydraulic pressure
applied to each side of the seal ring 72, the force in the closing
direction, i.e. toward impeller, is at least twice that in the opposite
direction.
Referring now to FIG. 4, an embodiment is shown wherein the case drain
fluid is not returned from the mud pump bearing cavity to the hydraulic
pump 15. In this case, instead of running the hydraulic fluid through the
case drain line 81 (typically 3/4 inch flexible hose) to the mud pump
bearing housing, there is a tee fitting 83 to which 1/2 inch return line
23A is connected to return case drain fluid to the hydraulic pump 15. But
also at the tee 83, a case drain fluid supply line 81A is connected. This
is a 1/4 inch line to the threaded port 78 in the mud pump housing. A plug
is installed in the port 79. A 1/64 inch orifice 84 is installed in the
line 81A as is a reverse flow check valve 86. The check valve prevents
flow of oil from the mud pump housing backward toward the tee fitting 83.
The orifice 84 limits the flow through the line 81A so that, if there is
any failure of the mud pump shaft seal assembly, the amount of oil which
would escape through it into the mud pit or well will be very much
restricted. In this way, maintenance of adequate hydraulic fluid in the
pump-motor system is assured, and any significant loss through the mud
pump assembly is avoided. At the same time, however, while the mud pump
assembly is in good working condition and the seal intact, the case drain
pressure from the hydraulic motor case 22 is applied and maintained in the
mud pump bearing assembly.
With the present invention, the seal assembly will be protected from
passage of muddy water through it, regardless of whether or not the
desired periodic greasing through the fitting 77 is neglected. At such
time as the seal assembly might begin to leak due to long term wear, any
leakage through it would be hydraulic fluid from the bearing housing into
the impeller cavity, not vice versa. Thus, the sealing surfaces would
continue to be lubricated in contrast to the situation which occurs with
conventional packing where, when a leak occurs, it is muddy water
containing various abrasives which leaks through the seal assembly toward
the bearings, resulting in increasingly rapid deterioration of the seal
and the bearings.
While the invention has been illustrated and described in detail in the
drawings and foregoing description, the same is to be considered as
illustrative and not restrictive in character, it being understood that
only the preferred embodiment has been shown and described and that all
changes and modifications that come within the spirit of the invention are
desired to be protected.
Top